1.1 This test method covers the detection of corrosive sulfur compounds in electrical insulating oils of petroleum origin. 1.2 Mineral insulating oils may contain substances that cause corrosion under certain conditions of use. This test method is designed to detect the presence of free sulfur and corrosive sulfur compounds by subjecting copper to contact with oil under prescribed conditions. 1.3 The values stated in inch-pound units are to be regarded as the standard. 1.4 This standard does not purport to address the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.